Dr. Bronner’s was a major contributor to a similar GMO labeling measure that was defeated last year in California. The soap company already has contributed more to the Washington measure than it did there.

The pro-labeling campaign in California raised more than $9 million, compared to $44 million for the anti-labeling side.

In California, Monsanto contributed more than $7 million, DuPont $4.9 million, Pepsico $2.1 million and Bayer CropScience more than $2 million.